Image Credit: https://www.americanenvironics.com/methods-of-fertilizer-application/

Results & Discussion

Overview

P-values for one-way and two-way ANOVAs for different treatments and treatment interactions for barley, canola, and wheat yields are reported in Table 2. Treatment means for the one-way ANOVAs, and statistically significant groupings are presented in Table 3.

Dryland and irrigated sites and nitrogen sources did not have significant treatment interactions, however 2008 precipitation was higher than average and could be a reason for the low interaction effects (Table 2). Nitrogen source and nitrogen timing/placement had statistically significant treatment interactions for all crop types (Table 2).

Table 2. Reported p-values for Statistical analyses of treatment effects for Barley, Wheat, and Canola crop yields. Statistical significance is indicated by the * ('*' = 0.01, '**' = 0.001, '***' = 0).

Table 3. Treatment means for 1 Way Treatment Effects for Barley, Wheat, and Canola. Means within treatments are not statistically significant (p>0.05) if they share the same letter.

Nitrogen Source and Nitrogen Timing/Placement

Crop yields for Urea and Environmentally Smart Nitrogen fertilizer sources were compared for fall banded, spring banded, and seed placed fertilizer timings/placements (Figure 8). For fall banded and spring banded fertilizer applications there was not a statistically significant difference in yield responses between Urea and Environmentally Smart Nitrogen fertilizer sources (Figure 8). Previous studies also found no consistent yield increases with the use of Environmentally Smart Nitrogen over Urea with spring banded fertilizer applications (1,2,4). Low soil temperature and moisture conditions in the fall may have prevented nitrogen losses from both Urea and Environmentally Smart Nitrogen, resulting in similar yield responses for fall banded fertilizer applications (5) (Figure 8). While Fall banded and Spring banded Environmentally Smart Nitrogen fertilizer did not provide yield gains, knowing that Environmentally Smart Nitrogen did not result in negative yield responses is important if Environmentally Smart Nitrogen is being applied for it’s environmental, rather than agronomic benefits. As expected, seed placed Environmentally Smart Nitrogen fertilizer had higher yields than Urea fertilizer, particularly for Canola (Figure 8).

Seed Placed Application: Nitrogen Sources and Nitrogen Rates

Crop yields for seed placed Blend, Environmentally Smart Nitrogen and Urea fertilizers were compared for different nitrogen rates in Figure 9. Starting at 60 kg N/ha for barley and canola, and 90 kg N/ha for wheat, Environmentally Smart Nitrogen and Blend fertilizer sources provided increased yields when seed placed (Figure 9, Table 4). As nitrogen rates increase, crop seedlings are more prone to seedling toxicity with conventional urea fertilizer (6). The use of Environmentally Smart Nitrogen or the Blend treatment allows for the nitrogen to be gradually released over the growing season, reducing the risk of seedling toxicity when the fertilizer is initially applied. Canola has the largest yield gains compared to barley and wheat for switching from Urea to the Environmentally Smart Nitrogen and Blend fertilizer sources when the fertilizer is seed placed (Figure 9, Table 4). The Blend fertilizer offers increased yield gains compared to Environmentally Smart Nitrogen at nitrogen rates of 60 and 90 kg N/ha for canola and barley crops (Table 4). However for wheat, and for a nitrogen rate of 120 kg N/ha for canola and barley Environmentally Smart Nitrogen provides the largest yield gains (Figure 9, Table 4).

Figure 9. Comparison of the impact of Blend, ESN (Environmentally Smart Nitrogen) and Urea fertilizers on barley, canola and wheat crop yields at different fertilizer rates. Means within nitrogen timing/placement treatments are not statistically significant (p>0.05) if they share the same letter.

Table 4. Yield Gains at different confidence levels for Selecting ESN or Blend Fertilizer Sources over Urea at Different Nitrogen Fertilizer Rates when Seed Placed. % Yield Gains are calculated by taking the increased yield and dividing it by the Urea yield treatment mean for the specified rate.

Blend and Environmentally Smart Nitrogen fertilizer sources will allow for producers to apply higher nitrogen rates without the effects of seedling toxicity, and see large yield gains of up to 25% for barley, 17% for wheat, and 116% for canola with 95% confidence depending on the nitrogen rate and the use of Blend or Environmentally Smart Nitrogen as a fertilizer (Table 4). At rates lower than 120 kg N/ha, the Blend fertilizer offers larger yield gains than Environmentally Smart Nitrogen for Barley (up to 14%) and Canola crops (up to 52%) (Table 4). With the cost of ESN fertilizer being $0.44 higher per kg than urea fertilizer, the Blend fertilizer source will provide higher economic returns for producers by using less Environmentally Smart Nitrogen while still providing high yield gains.

Future Directions

Future analyses will look further at the interactions between nitrogen sources and site irrigation for different crops, fertilizer rates, and fertilizer timings/placements. In addition, response variables such as grain protein and canola oil will be analyzed to determine if Environmentally Smart Nitrogen has an impact on crop quality. Finally, results from multiple years will be analyzed and compared to determine how differing environmental conditions from year to year impacts Environmentally Smart Nitrogen fertilizer effectiveness.

Disclaimer: This website is a project for REN R 690 at the University of Alberta, and was developed solely to fulfill the requirements for the course.